Structure for controlling the aero-acoustic environment in an aircraft weapons bay

ABSTRACT

An aircraft comprises a weapons bay, the weapons bay comprising a cavity having an opening through which stores may be deployed, and a door assembly for exposing/closing the opening of the cavity. A first store is held in the cavity via a launcher and a first structure is disposed inside the cavity, for controlling the aero-acoustic environment. The first structure for controlling the aero-acoustic environment is removeably mounted in the weapons bay, such that if the first store is exchanged for a second, different, store, the structure for controlling the aero-acoustic environment may be unmounted from the weapons bay and removed, to be exchanged for a second, different, structure for controlling the aero-acoustic environment.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/854,471, filed Dec. 26, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/587,968, filed Dec. 31, 2014 and issued on May22, 2018, U.S. Pat. No. 9,975,635, which claims priority to GBApplication 1400179.6, filed on Jan. 6, 2014, all of which areincorporated herein by reference in their entireties for all purposes.

TECHNICAL FIELD

The present invention relates to aircraft weapons bays, a structure forcontrolling the aero-acoustic environment in an aircraft weapons bay,and methods of controlling the aero-acoustic environment in an aircraftweapons bay.

BACKGROUND

An aircraft weapons bay typically comprises a cavity having an openingthrough which stores may be deployed, and a door assembly forexposing/closing the opening of the cavity. The environment in andaround the cavity, when the doors are opened during flight, can besevere. In particular, the pressure in the cavity can fluctuatesignificantly. The pressure fluctuations can give rise to significantaero-acoustic effects (e.g. audible noise, vibrations etc.).

Extreme aero-acoustic environments are undesirable for a number ofreasons. For example, the lifetime of stores in the weapons bay may bereduced (e.g. by vibration damaging the energetic materials within thestore (for example warhead and rocket motor)), electronics or otherequipment in the aircraft and/or in the store may become damaged, or theflowfield may be sufficiently disrupted to undesirably affect the launchtrajectory of the store.

Efforts to alleviate the severity of the aero-acoustic environment inthe weapons bay have tended to focus on permanent modifications to theaircraft structure, for example by placing control surfaces upstream ofthe weapons bay, or by re-shaping the boundaries of the weapons bay.These have been found to have only a moderately beneficial effect on theaero-acoustics. Furthermore, these are typically generic solutions, andtend not to be tailored to specific stores/configurations of the weaponsbay.

SUMMARY

It is desirable to provide an aircraft weapons bay which reduces ormitigates at least some of the above-mentioned problems.

According to a first aspect of the invention, there is provided anaircraft comprising a weapons bay, the weapons bay comprising a cavityhaving an opening through which stores may be deployed, and a doorassembly for exposing/closing the opening of the cavity. A first storeheld in the cavity (e.g. via a launcher) and a first structure, disposedin the cavity, for controlling the aero-acoustic environment. By placingthe structure for controlling the aero-acoustic environment inside thecavity (rather than, for example upstream of it) the structure candirectly influence the flowfield in the cavity. This may enable moreeffective control of the aero-acoustic environment. The first structurefor controlling the aero-acoustic environment is removeably mounted inthe weapons bay, such that if the first store is exchanged for a second,different, store, the structure for controlling the aero-acousticenvironment may be unmounted from the weapons bay and removed, to beexchanged for a second, different, structure for controlling theaero-acoustic environment. Such an arrangement enables differentstructures for controlling the aero-acoustic environment to be fitted inthe weapons bay dependent on, for example, the choice/layout of storesin the weapons bay. The structure for controlling the aero-acousticenvironment can thus be tailored to the specific weapon bay it is fittedin (e.g. dependent on both the shape of the weapon bay and thenature/layout of the store(s)), rather than requiring a re-design of theaircraft weapons bay itself.

The first and second structures for controlling the aero-acousticenvironment are preferably independent of the aircraft structure. Thestructures for controlling the aero-acoustic environment may beattachable to/detachable from the weapons bay. The structures forcontrolling the aero-acoustic environment are preferably repeatedlyattachable to/detachable from the weapons bay.

The structures for controlling the aero-acoustic environment may beassociated with the respective store (for example the structure forcontrolling the aero-acoustic environment may be indirectly coupled tothe store itself). The structures for controlling the aero-acousticenvironment may be associated with the launcher of the store. Thestructures for controlling the aero-acoustic environment are preferablyassociated with the respective store and/or launcher such that thestructure is installed in the weapons bay simultaneously with thefitting of, or preparations to fit, the respective store and/orlauncher. The structure for controlling the aero-acoustic environmentmay be connected to the launcher. The structure for controlling theaero-acoustic environment may be connected to the launcher mounting.Having the structure for controlling the aero-acoustic environmentassociated with the launcher enables the structure for controlling theaero-acoustic environment to be easily fitted inside the cavity (forexample when fitting the launcher to the weapons bay). The structure forcontrolling the aero-acoustic environment preferably remains in theweapons bay after launch of the respective store. The structure forcontrolling the aero-acoustic environment may be associated with therespective store and/or the launcher in such a way that it can be fittedwith the store and/or launcher, but remains in the weapons bay afterlaunch of the store.

The first structure for controlling the aero-acoustic environment isdisposed inside the cavity. The first structure for controlling theaero-acoustic environment is preferably exposed to airflow within thecavity. The first structure for controlling the aero-acousticenvironment may therefore not need to be reliant on control devicesexternal to the weapons bay. The first structure for controlling theaero-acoustic environment is preferably wholly inside the cavity.

The first structure for controlling the aero-acoustic environment ispreferably a noise reduction structure. By placing a noise reductionstructure inside the cavity the structure can directly influence theflowfield in the cavity that might otherwise be the source of excessivenoise.

The first structure for controlling the aero-acoustic environment, haspreferably been designed to reduce aero-acoustic effects when the firststore is held in the cavity. The second structure for controlling theaero-acoustic environment, has preferably been designed to reduceaero-acoustic effects when the second store is held in the cavity.

The structures for controlling the aero-acoustic environment may take anumber of forms. It will be appreciated that features described hereinwith reference to ‘the structure for controlling the aero-acousticenvironment in the weapons bay’, are equally applicable to both thefirst structure and/or the second, different, structure, for controllingthe aero-acoustic environment in the weapons bay.

In some embodiments, the structure for controlling the aero-acousticenvironment may comprise a lateral wall extending in a direction acrossthe width of the cavity and extending from the launcher towards theopening. The lateral wall may be positioned to at least one side of thestore. The lateral wall may be positioned either side of the store. Thelateral wall may, in principle, be two separate elements either side ofthe store. More preferably, the lateral wall is a single elementextending either side of the store. The lateral wall may have a cut-awayto provide free passage of the store. A lateral wall is thought todisrupt airflow in the cavity. In particular, the lateral wall mayrestrict the distance over which pressure fluctuations can propagatewithin the weapons bay during use, thereby reducing aero-acousticeffects. The lateral wall preferably extends from the launcher to theopening (for example to the underside of the bay doors when closed).Having the lateral wall extend the full depth of the cavity is thoughtto maximize the aero-acoustic-reducing effect. The lateral wall mayextend across only some of the width of the cavity. The lateral wall mayextend across the full width of the cavity. The structure forcontrolling the aero-acoustic environment may comprise a flangeextending from the lateral wall in a direction parallel to the openingof the cavity. The flange may thereby reduce the extent of the cavityexposed to freestream airflow during use (when the bay doors are open),thus reducing noise. The structure for controlling the aero-acousticenvironment may comprise a plurality of the above-mentioned lateralwalls, each being spaced apart along the length of the weapons bay. Insome embodiments the lateral walls may be thin walls. In someembodiments they may be relatively thick. For example the wall may besufficiently thick, such that the face of the wall in the depthdirection can be used to contribute to noise reduction. The lateralswall(s) may be arranged such that they are inclined to the air flow inthe weapons bay during use. The laterals wall(s) may, in principle, beat any angle to the longitudinal axis of the weapons bay. The lateralswall(s) may be at >45 degrees to the longitudinal axis of the weaponsbay. The laterals wall(s) may be generally downwardly extending from theroof of the weapons bay.

In other embodiments, the structure for controlling the aero-acousticenvironment may comprise an infill-surface arranged to reduce the extentof the cavity exposed to freestream airflow during use. The in-fillsurface may extend substantially parallel to the opening. The in-fillsurface may extend across the majority of the opening. The structure forcontrolling the aero-acoustic environment may further comprise asurround surface. The surround surface may extend from the infillsurface and behind the store. The surround surface may thereby create achannel out of which the store may be deployed, whilst still limitingthe extent of the cavity exposed to the freestream airflow.

In other embodiments, the structure for controlling the aero-acousticenvironment may comprise a baffle (directly or indirectly) between thestore and the side wall of the cavity. The baffle is any structureadapted to reduce the noise (in comparison to the baffle being absent).The baffle may comprise a lateral wall extending in a direction acrossthe width of the cavity. The baffle may comprise a longitudinal wallextending in a direction along the length of the cavity. The wall(s) maybe arranged such that they are inclined to the flow in the weapons bayduring use. The lateral and longitudinal wall(s) may, in principle, beat any angle to the respective longitudinal and lateral axes of theweapons bay. The wall(s) may be at >45 degrees to the respective axis ofthe weapons bay. The wall(s) may be generally downwardly extending fromthe roof of the weapons bay.

In some embodiments, the baffles effectively join to form a divider.Accordingly, the structure for controlling the aero-acoustic environmentmay comprise a divider for dividing the cavity into a plurality ofsecondary cavities. The divider preferably restricts the distance overwhich pressure fluctuations can propagate within the weapons bay duringuse, thereby reducing noise. The divider may comprise alaterally-extending wall. The divider may comprise alongitudinally-extending wall. The divider may comprise both laterallyand longitudinally extending walls.

In all of the above-described arrangements, the structure forcontrolling the aero-acoustic environment may comprise an unperforatedsurface. However, the structure for controlling the aero-acousticenvironment preferably includes at least one perforation, and morepreferably a plurality of perforations. Embodiments comprising aperforated surface are considered especially beneficial as theperforated surface may alleviate aerodynamic loads on the structure forcontrolling the aero-acoustic environment and/or improve theaero-acoustic control function of the structure. The structure forcontrolling the aero-acoustic environment may include an access hatchfor providing access to the other side of the structure for controllingthe aero-acoustic environment. This is especially beneficial because itstill enables the weapons bay to act as an access point to variousaircraft systems. The structure for controlling the aero-acousticenvironment may include a cut out for accommodating other furniture inthe weapons bay (for example pipework or equipment attached to thesidewalls of the weapons bay). A cut out may be defined as a variationof the form of a component that allows the component to be placedaround, against or in close proximity to a second component in a mannerthat would otherwise not be possible.

The aircraft may comprise a plurality of stores held in the cavity. Thestructure for controlling the aero-acoustic environment may have beendesigned to reduce aero-acoustic effects when the plurality of stores isheld in the cavity. The structure for controlling the aero-acousticenvironment is removeably mounted in the weapons bay, such that if theplurality of stores are exchanged for a second, different, plurality ofstores, the structure for controlling the aero-acoustic environment maybe unmounted from the weapons bay and removed, to be exchanged for asecond, different, structure for controlling the aero-acousticenvironment. The plurality of stores, may all be of the same type, ormay be a collection of different types of store.

According to another aspect of the invention there is provided aremoveable structure for controlling the aero-acoustic environment in aweapons bay, for use as the first structure for controlling theaero-acoustic environment a described herein.

In principle, features described herein with reference to embodiments ofthe invention may be combined. For example in an embodiment comprises aplurality of stores, each of a plurality of stores may be disposed in arespective secondary cavity, and the structure for controlling theaero-acoustic environment may also comprise a plurality of lateralwalls, each lateral wall extending either side of a respective store.

The aircraft may be manned (for example a piloted aircraft). Theaircraft may be unmanned (i.e. a UAV). The aircraft may be a fixed wingaircraft. The aircraft may be a rotary wing aircraft.

The aircraft may be arranged to travel faster than Mach 0.1, and morepreferably faster than Mach 0.5. The aircraft may be a super-sonicaircraft.

The store may be a guided weapon, a bomb, or other store such as adecoy, jammer, or fuel tank.

According to another aspect of the invention, there is provided a storein combination with a structure for controlling the aero-acousticenvironment, for use as the store and the structure for controlling theaero-acoustic environment described herein.

According to another aspect of the invention, there is provided a kit ofparts for controlling the aero-acoustic environment in an aircraftweapons bay. The kit comprises: a first store, a second, different,store, a first structure for removeably mounting in a cavity of theweapons bay, the first structure being pre-designed to reduceaero-acoustic effects in the weapons bay when the first store is held inthe weapons bay; and a second, different, structure for removeablymounting in the cavity of the weapons bay, the second structure beingpre-designed to reduce aero-acoustic effects in the weapons bay when thesecond store is held in the weapons bay; such that the first and secondstructures for controlling the aero-acoustic environment may beexchanged in dependence on whether the first or second store is to beheld in the weapons bay.

According to another aspect of the invention, there is provided a methodof tailoring two structures for controlling the aero-acousticenvironment in an aircraft weapons bay, the method comprising the stepsof: assessing the aircraft weapons bay; assessing the layout of thefirst store in the weapons bay; and designing a first removeablestructure for controlling the aero-acoustic environment such that, whendisposed inside the weapons bay, the first structure would reduce noisegenerated by the weapons bay and by the first store in the bay. Themethod may comprise the step of assessing a second store when it is inthe weapons bay instead of the first store and designing a secondremoveable structure for controlling the aero-acoustic environment suchthat, when disposed inside the weapons bay, the second structure wouldreduce aero-acoustic effects generated by the weapons bay and the secondstore in the bay. Weapons bays are typically designed to have theflexibility to accommodate a variety of different stores. Thus, theretends to be some spare space in a bay when occupied by any one specifictype of store or specific layout of stores. Tailoring the structures forcontrolling the aero-acoustic environment (for use with the respectivefirst or second store), enables this otherwise unoccupied space to beused for reducing aero-acoustic effects.

According to another aspect of the invention, there is provided a methodof modifying a weapons bay on an aircraft to reduce aero-acousticeffects generated by the weapons bay, the method comprising the stepsof: providing an aircraft weapons bay comprising a cavity having anopening through which stores may be deployed, and a door assembly forexposing/closing the opening of the cavity, unmounting a first,removeable, structure for controlling the aero-acoustic environmentinside the cavity, and subsequently mounting a second structure forcontrolling the aero-acoustic environment inside the cavity, to replacethe first structure. The first structure is pre-designed for reducingaero-acoustic effects when the first store is held in the cavity and thesecond structure, is pre-designed for reducing aero-acoustic effectswhen a second, different, store is held in the cavity.

Any features described with reference to one aspect of the invention areequally applicable to any other aspect of the invention, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the invention will now be described by way ofexample only and with reference to the accompanying drawings, of which:

FIGS. 1a and 1b are schematic plan and sectional views respectively, ofan aircraft weapons bay according to a first embodiment of theinvention;

FIGS. 2a and 2b are schematic plan and sectional views respectively, ofan aircraft weapons bay according to a second aspect of the invention;

FIGS. 3a and 3b are schematic plan and sectional views respectively, ofan aircraft weapons bay according to a third aspect of the invention;and

FIGS. 4a and 4b are schematic plan and sectional views respectively, ofan aircraft weapons bay according to a fourth aspect of the invention.

DETAILED DESCRIPTION

FIG. 1a is a plan view of a weapons bay in the underside of an aircraft(not shown) according to a first embodiment of the invention. FIG. 1b isa section view, taken through the line A-A. The weapons bay 1 isgenerally cuboidal and comprises a cavity 3 (denoted by dotted lines inFIGS. 1a and 1b ). The weapons bay has side-walls 7 and an opening 5through which stores 9 may be deployed. The weapons bay also comprises adoor assembly (not shown) for exposing/closing the opening 5 of thecavity 3. Four missiles 9 are held in the cavity via a launcher 11 fromwhich each missile can be independently launched. The launcher 11attaches to the roof 13 of the weapons bay 1 by way of a launchermounting. The environment in and around the cavity, when the doors areopened during flight, can be severe. In particular, there can besignificant aero-acoustic effects. Extreme aero-acoustic effects areundesirable, and the weapons bay according to the first embodiment,comprises a structure for controlling the aero-acoustic environment 15to mitigate excessive aero-acoustic effects.

The structure for controlling the aero-acoustic environment comprisestwo baffles 17 a, 17 b arranged between the stores. A first baffle 17 ais a lateral wall extending in a direction across the width of thecavity (but not joining either sidewall). The second baffle is alongitudinal wall extending in a direction along the length of thecavity (but not joining either end wall). Both baffles extend downwardlyfrom the launcher 11 to the opening, to maximize their effect on theflow in the cavity. Both the baffles are contoured (not shown in FIGS.1a-1b ) and are both perforated to reduce the aerodynamic loading onthem and to improve their function as baffles (i.e. in reducing noise).

In contrast to prior art structures for controlling the aero-acousticenvironment in weapons bays, the structure for controlling theaero-acoustic environment 15 is located wholly inside the cavity 3. Thepresent invention recognizes that some of the space in the cavity 3 canbe used for controlling aero-acoustic effects, and that by placing astructure for controlling such effects inside the cavity, the structurecan directly influence the flowfield in the cavity.

In contrast to prior art structures for controlling the aero-acousticenvironment for weapons bays, the structure for controlling theaero-acoustic environment 15 is also removeably mounted in the weaponsbay. In the first embodiment, the noise-reducing element is attached tothe launcher 11. The structure for controlling the aero-acousticenvironment can therefore be installed in the weapons bay when fittingthe launcher, and can be removed from the weapons bay when removing thelauncher (e.g. after use of the store or if replacement of the store isotherwise required). Since the structure for controlling theaero-acoustic environment is separate from the aircraft structure, itcan be tailored to the specific weapon bay it is fitted in, taking intoaccount the nature, and layout of the stores, rather than requiring are-design of the aircraft weapons bay itself.

FIG. 2a is a plan view of a weapons bay in the underside of an aircraft(not shown) according to a second embodiment of the invention. FIG. 2bis a section view, taken through the line A-A. Features in the secondembodiment of the invention that correspond to similar features in thefirst embodiment of the invention, are shown with the same referencenumerals as in the first embodiment, but with the addition of the prefix‘1’ (or ‘10’ where appropriate).

In contrast to the first embodiment, the structure for controlling theaero-acoustic environment 115 in FIGS. 2a and 2b comprises additionallateral and longitudinal walls 117 a/b such that the cavity 105 isdivided into four secondary cavities 119, each secondary cavitycontaining a store 109. Dividing the cavity into secondary cavities isthought to reduce noise by restricting the distance over which pressurefluctuations can propagate within the weapons bay during use.

In common with the structure for controlling the aero-acousticenvironment in the first embodiment, the structure for controlling theaero-acoustic environment is connected to the launcher 111 and is thusremoveable from the aircraft weapons bay.

FIG. 3a is a plan view of a weapons bay in the underside of an aircraft(not shown) according to a third embodiment of the invention. FIG. 3b isa section view, taken through the line B-B. Features in the thirdembodiment of the invention that correspond to similar features in thefirst embodiment of the invention, are shown with the same referencenumerals as in the first embodiment, but with the addition of the prefix‘2’ (or ‘20’ where appropriate).

In contrast to the second embodiment, the structure for controlling theaero-acoustic environment 215 in FIGS. 3a and 3b comprises a lateralwall 220 extending in a direction across the width of the cavity 203(but not joining either sidewall). The lateral wall 220 extends as asingle element across the majority of the width of the cavity includingbehind the missile 209. The lateral wall extends downwardly from thelauncher 211 towards the opening 205. The downward extent of the lateralwall varies with distance across the cavity and is reduced in the centerregion where the wall 220 passes between the missile 209 and launcher211 to form a cut-away. Either side of the missile 209 the wall extendsdownwardly from the launcher 211 to the opening 205, to maximize itseffect on the flow in the cavity. Flanges 222 extend parallel to theopening 205 at the downward edge of the wall 220 (except in the centerregion) to further limit the extent of the cavity exposed to thefreestream airflow.

In common with the structure for controlling the aero-acousticenvironment in the first and second embodiments, the structure forcontrolling the aero-acoustic environment of the third embodiment isconnected to the launcher 211 and is thus removable from the aircraftweapons bay.

FIG. 4a is a plan view of a weapons bay in the underside of an aircraft(not shown) according to a fourth embodiment of the invention. FIG. 4bis a section view, taken through the line BB. Features in the fourthembodiment of the invention that correspond to similar features in thefirst embodiment of the invention, are shown with the same referencenumerals as in the first embodiment, but with the addition of the prefix‘3’ (or ‘30’ where appropriate).

In contrast to the first, second and third embodiments, the structurefor controlling the aero-acoustic environment 315 in FIGS. 3a and 3bcomprises an infill-surface 332. The infill-surface 332 extends acrossthe length and width of the cavity 303, excluding the area above themissile, at the level of, and substantially parallel to, the opening 305(it can be thought of as a version of the flange 222 of the thirdembodiment, but taken to an extreme extension. An inner edge 332 a ofinfill-surface 332 surrounds the missile 309. A surround surface 330extends from the inner-edge 332 a of the infill-surface and behind themissile 309 to form a recess in which the missile 309 is located priorto launch. The recess formed by surround surface 330 is shaped toaccommodate the missile 309, including its fins 334 (shown in dottedlines), when located on the launcher 311. Providing the infill surface332, particularly in combination with the surround surface 330, reducesthe extent of the cavity exposed to the freestream airflow during use.The recess formed by the surround surface 330 creates a channel out ofwhich the missile 309 may be deployed.

In common with the structure for controlling the aero-acousticenvironment in the first, second, and third embodiments, the structurefor controlling the aero-acoustic environment of the fourth embodimentis connected to the launcher 211 and is thus removable from the aircraftweapons bay.

Whilst the present invention has been described and illustrated withreference to particular embodiments, it will be appreciated by those ofordinary skill in the art that the invention lends itself to manydifferent variations not specifically illustrated herein. For example,the cavity need not necessarily be cuboidal, and may be any shape. Thewalls need not be vertical (for example they may be inclined at an acuteangle to the freestream flow). The structure for controlling theaero-acoustic environment need not necessarily be attached to thelauncher. It may, for example, be releasable attached to the side wallof the weapons bay. Furthermore, features described with reference toone embodiment may be equally applicable to another embodiment. Forexample, the arrangement in FIGS. 3a and 3b may be applied to each ofthe stores in FIGS. 2a and 2 b.

Where in the foregoing description, integers or elements are mentionedwhich have known, obvious or foreseeable equivalents, then suchequivalents are herein incorporated as if individually set forth.Reference should be made to the claims for determining the true scope ofthe present invention, which should be construed so as to encompass anysuch equivalents. It will also be appreciated by the reader thatintegers or features of the invention that are described as preferable,advantageous, convenient or the like are optional and do not limit thescope of the independent claims.

We claim:
 1. An aircraft comprising: a weapons bay, the weapons baycomprising a cavity having an opening through which stores may bedeployed, and a door assembly for exposing/closing the opening of thecavity, a first store held in the cavity via a launcher; and a firststructure, disposed inside the cavity, for controlling the aero-acousticenvironment, wherein the first structure for controlling theaero-acoustic environment is removeably mounted in the weapons bay, suchthat when the first store is exchanged for a second, different, store,the structure for controlling the aero-acoustic environment may beunmounted from the weapons bay and removed, to be exchanged for asecond, different, structure for controlling the aero-acousticenvironment.
 2. An aircraft according to claim 1, wherein the firststructure comprises a baffle, wherein the baffle is provided between thefirst store and a side wall of the cavity.
 3. An aircraft according toclaim 2, wherein the baffle comprises a lateral wall extending in adirection across a width of the cavity and extending from the launchertowards the opening of the cavity.
 4. An aircraft according to claim 2,wherein the baffle comprises a longitudinal wall extending in adirection along a length of the cavity and extending from the launchertowards the opening of the cavity.
 5. An aircraft according to claim 1,wherein the first structure comprises two baffles, wherein a firstbaffle comprises a lateral wall extending across the width of the cavityand extending from the launcher towards the opening of the cavity, and asecond baffle comprises a longitudinal wall extending along the lengthof the cavity, and extending from the launcher towards the opening ofthe cavity.
 6. An aircraft according to claim 5, wherein the aircraftcomprises a second store, and wherein the first baffle and the secondbaffle join to form a divider between the first and the second stores,thereby dividing the cavity into at least two sub-cavities, each cavityhousing a store.
 7. An aircraft according claim 1, wherein the firststructure comprises a multiplicity of baffles, and wherein each of thebaffles comprises either a lateral wall extending across the width ofthe cavity and extending from the launcher towards the opening of thecavity, or a longitudinal wall extending along the length of the cavityand extending from the launcher towards the opening of the cavity.
 8. Anaircraft according to claim 7, wherein the multiplicity of baffles jointo form a plurality of dividers, thereby dividing the cavity into aplurality of sub-cavities, and wherein the aircraft comprises aplurality of stores, each store occupying a sub-cavity.
 9. An aircraftaccording to claim 1, wherein the first structure for controlling theaero-acoustic environment, has been designed to reduce aero-acousticeffects when the first store is held in the cavity.
 10. An aircraftaccording to claim 1, wherein the first structure for controlling theaero-acoustic environment is associated with the first store and/or thelauncher, such that the first structure for controlling theaero-acoustic environment can be installed in the weapons baysimultaneously with the fitting of the first store and/or the launcher.11. A store in combination with a structure for controlling theaero-acoustic environment, for use as the first store and the firststructure for controlling the aero-acoustic environment, in an aircraftcomprising a weapons bay, the weapons bay comprising a cavity having anopening through which stores are able to be deployed, and a doorassembly for exposing/closing the opening of the cavity; a first storeheld in the cavity via a launcher; and a first structure, disposedinside the cavity, for controlling the aero-acoustic environment,wherein the first structure for controlling the aero-acousticenvironment is removeably mounted in the weapons bay, such that when thefirst store is to be exchanged for a second, different, store, the firststructure for controlling the aero-acoustic environment is able to beunmounted from the weapons bay and removed, to be exchanged for asecond, different, structure for controlling the aero-acousticenvironment.
 12. A removeable structure for controlling theaero-acoustic environment in a weapons bay, for use as the firststructure for controlling the aero-acoustic environment, in an aircraftcomprising a weapons bay, the weapons bay comprising a cavity having anopening through which stores are able to be deployed, and a doorassembly for exposing/closing the opening of the cavity; a first storeheld in the cavity via a launcher; and a first structure, disposedinside the cavity, for controlling the aero-acoustic environment,wherein the first structure for controlling the aero-acousticenvironment is removeably mounted in the weapons bay, such that when thefirst store is to be exchanged for a second, different, store, the firststructure for controlling the aero-acoustic environment is able to beunmounted from the weapons bay and removed, to be exchanged for asecond, different, structure for controlling the aero-acousticenvironment.